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Infectious Disease and Microbiology – Candidiasis
Candida is a yeast that forms part of the normal flora of the skin, gastrointestinal tract, and genitourinary tract. Although often harmless, Candida species can cause both superficial mucocutaneous infections and life-threatening systemic disease, particularly in immunocompromised individuals. Candida has become an increasingly important cause of bloodstream infections in hospitalized patients.
Candidal infections affect individuals of all ages but are more common in infants, elderly patients, and pregnant women. In U.S. hospitals, Candida accounts for approximately 9% of bloodstream infections. While Candida albicans remains the most frequently isolated species, non-albicans species are increasingly encountered, including Candida parapsilosis, Candida glabrata, and Candida tropicalis.
Major risk factors include immunosuppression and neutropenia, malignancy, HIV/AIDS, major burns, prolonged antibiotic use, indwelling intravenous catheters, chemotherapy, solid organ or bone marrow transplantation, total parenteral nutrition, chronic renal failure with hemodialysis, gastrointestinal perforation, diabetes mellitus, pregnancy, and glucocorticoid therapy. Prevention strategies focus on judicious antibiotic use and removal of unnecessary central venous catheters.
Candidemia may arise from disruption of mucosal barriers along the gastrointestinal tract or from colonization of intravascular devices. More than 150 Candida species exist, but clinically significant species include Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, Candida krusei, Candida guilliermondii, and Candida lusitaniae. Candida albicans accounts for more than half of candidemia cases.
Clinical manifestations vary by site of infection. Vulvovaginal candidiasis presents with pruritus, irritation, dysuria, dyspareunia, and a white “cheesy” discharge. Oropharyngeal candidiasis (thrush) may cause oral discomfort, altered taste, or may be asymptomatic. Candida esophagitis presents with nausea, retrosternal chest pain, odynophagia, and dysphagia. Invasive candidiasis and candidemia may present with fever, hypotension, tachycardia, altered mental status, and signs of severe sepsis, particularly in immunocompromised patients.
Physical findings depend on the affected organ. Vulvovaginal candidiasis shows vulvar or vaginal erythema and characteristic discharge. Oral candidiasis presents with white plaques on the tongue and palate that leave an erythematous base when scraped. Esophageal involvement may occur without oral lesions. Candidemia ranges from isolated fever to septic shock.
Diagnosis of vulvovaginal and oral candidiasis is often clinical, supported by microscopic examination of KOH preparations showing yeast with or without pseudohyphae. Vaginal pH typically remains normal (4–4.5). Esophageal candidiasis may require endoscopy and biopsy, although empiric treatment is often initiated in high-risk patients with suggestive symptoms. Candidemia is diagnosed by positive blood cultures; Candida in blood should never be considered a contaminant. Susceptibility testing is important in serious infections or when there is treatment failure. Imaging may be required to evaluate complications such as endocarditis, central nervous system involvement, hepatosplenic candidiasis, pneumonia, or peritonitis. All patients with candidemia should undergo ophthalmologic examination due to the risk of endophthalmitis.
Treatment depends on the site and severity of infection. Vulvovaginal candidiasis can be treated with topical azoles (e.g., butoconazole cream for 3–7 days) or a single 150 mg oral dose of fluconazole, with longer courses in severe or immunocompromised cases. Oropharyngeal candidiasis is treated with nystatin suspension, clotrimazole troches, or fluconazole 100–200 mg daily until several days after symptom resolution. Candida esophagitis is treated with fluconazole (400 mg loading dose followed by 200–400 mg daily for 7–14 days), given orally or intravenously.
Management of candidemia depends on host factors. Stable, non-neutropenic patients without prior antifungal exposure may receive fluconazole (800 mg loading dose, then 400 mg daily). Unstable patients, neutropenic individuals, or those with prior antifungal exposure should receive an echinocandin (caspofungin, micafungin, or anidulafungin), voriconazole, or lipid-formulation amphotericin B. Therapy should be adjusted based on species identification and susceptibility. Notably, Candida krusei is resistant to fluconazole; Candida glabrata often exhibits azole resistance; Candida parapsilosis may have higher minimum inhibitory concentrations to echinocandins; and Candida lusitaniae may be resistant to amphotericin B. Treatment should continue for at least two weeks after clearance of blood cultures and resolution of symptoms, with removal of infected catheters or other sources.
Infectious disease consultation is recommended for candidemia and neutropenic patients. Pharmacologic monitoring is essential due to potential drug interactions and QT prolongation with triazoles. Daily blood cultures should be obtained until clearance is documented.
Prognosis depends on early recognition and prompt antifungal therapy. Delayed treatment significantly increases mortality, which may exceed 40% when therapy is initiated three or more days after documented candidemia. Complications include renal failure, endocarditis, endophthalmitis, meningitis, peritonitis, pericarditis, abscess formation, esophageal perforation, and death.
Candida is a yeast that forms part of the normal flora of the skin, gastrointestinal tract, and genitourinary tract. Although often harmless, Candida species can cause both superficial mucocutaneous infections and life-threatening systemic disease, particularly in immunocompromised individuals. Candida has become an increasingly important cause of bloodstream infections in hospitalized patients.
Candidal infections affect individuals of all ages but are more common in infants, elderly patients, and pregnant women. In U.S. hospitals, Candida accounts for approximately 9% of bloodstream infections. While Candida albicans remains the most frequently isolated species, non-albicans species are increasingly encountered, including Candida parapsilosis, Candida glabrata, and Candida tropicalis.
Major risk factors include immunosuppression and neutropenia, malignancy, HIV/AIDS, major burns, prolonged antibiotic use, indwelling intravenous catheters, chemotherapy, solid organ or bone marrow transplantation, total parenteral nutrition, chronic renal failure with hemodialysis, gastrointestinal perforation, diabetes mellitus, pregnancy, and glucocorticoid therapy. Prevention strategies focus on judicious antibiotic use and removal of unnecessary central venous catheters.
Candidemia may arise from disruption of mucosal barriers along the gastrointestinal tract or from colonization of intravascular devices. More than 150 Candida species exist, but clinically significant species include Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, Candida krusei, Candida guilliermondii, and Candida lusitaniae. Candida albicans accounts for more than half of candidemia cases.
Clinical manifestations vary by site of infection. Vulvovaginal candidiasis presents with pruritus, irritation, dysuria, dyspareunia, and a white “cheesy” discharge. Oropharyngeal candidiasis (thrush) may cause oral discomfort, altered taste, or may be asymptomatic. Candida esophagitis presents with nausea, retrosternal chest pain, odynophagia, and dysphagia. Invasive candidiasis and candidemia may present with fever, hypotension, tachycardia, altered mental status, and signs of severe sepsis, particularly in immunocompromised patients.
Physical findings depend on the affected organ. Vulvovaginal candidiasis shows vulvar or vaginal erythema and characteristic discharge. Oral candidiasis presents with white plaques on the tongue and palate that leave an erythematous base when scraped. Esophageal involvement may occur without oral lesions. Candidemia ranges from isolated fever to septic shock.
Diagnosis of vulvovaginal and oral candidiasis is often clinical, supported by microscopic examination of KOH preparations showing yeast with or without pseudohyphae. Vaginal pH typically remains normal (4–4.5). Esophageal candidiasis may require endoscopy and biopsy, although empiric treatment is often initiated in high-risk patients with suggestive symptoms. Candidemia is diagnosed by positive blood cultures; Candida in blood should never be considered a contaminant. Susceptibility testing is important in serious infections or when there is treatment failure. Imaging may be required to evaluate complications such as endocarditis, central nervous system involvement, hepatosplenic candidiasis, pneumonia, or peritonitis. All patients with candidemia should undergo ophthalmologic examination due to the risk of endophthalmitis.
Treatment depends on the site and severity of infection. Vulvovaginal candidiasis can be treated with topical azoles (e.g., butoconazole cream for 3–7 days) or a single 150 mg oral dose of fluconazole, with longer courses in severe or immunocompromised cases. Oropharyngeal candidiasis is treated with nystatin suspension, clotrimazole troches, or fluconazole 100–200 mg daily until several days after symptom resolution. Candida esophagitis is treated with fluconazole (400 mg loading dose followed by 200–400 mg daily for 7–14 days), given orally or intravenously.
Management of candidemia depends on host factors. Stable, non-neutropenic patients without prior antifungal exposure may receive fluconazole (800 mg loading dose, then 400 mg daily). Unstable patients, neutropenic individuals, or those with prior antifungal exposure should receive an echinocandin (caspofungin, micafungin, or anidulafungin), voriconazole, or lipid-formulation amphotericin B. Therapy should be adjusted based on species identification and susceptibility. Notably, Candida krusei is resistant to fluconazole; Candida glabrata often exhibits azole resistance; Candida parapsilosis may have higher minimum inhibitory concentrations to echinocandins; and Candida lusitaniae may be resistant to amphotericin B. Treatment should continue for at least two weeks after clearance of blood cultures and resolution of symptoms, with removal of infected catheters or other sources.
Infectious disease consultation is recommended for candidemia and neutropenic patients. Pharmacologic monitoring is essential due to potential drug interactions and QT prolongation with triazoles. Daily blood cultures should be obtained until clearance is documented.
Prognosis depends on early recognition and prompt antifungal therapy. Delayed treatment significantly increases mortality, which may exceed 40% when therapy is initiated three or more days after documented candidemia. Complications include renal failure, endocarditis, endophthalmitis, meningitis, peritonitis, pericarditis, abscess formation, esophageal perforation, and death.
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